Top silo unloaders are suspended from a tripod which is supported upon the top of the silo wall and extends into the domed silo roof. Those silo unloaders which have a drive ring are provided with three horizontal support arms the outer ends of which are outside the perimeter of the drive ring, and suspension cables which are trained over sheaves in the upper part of the tripod are secured to the outer ends of the support arms so that the silo unloader may be moved vertically in the silo by operation of a winch near the base of the silo.
When a silo is to be filled, the unloader must be raised high enough to avoid or minimize interference with the incoming material.
If the silo unloader is too low some of the incoming material will drop onto the cutter-conveyor pickup arm and other components. This results in severe overloading of the supporting tripod and can cause damage to or collapse of the tripod. In addition, these lower silo unloader components will intercept or deflect the incoming silage stream and thus prevent the desired even and symmetrical placement of material across the entire area of the silo.
The silo unloader discharge chute may be removed; but even so the vertical height of the unloader and the span across the support arms usually prevents raising the unloader high enough to prevent the pickup arm from interfering seriously with the incoming material.
U.S. Pat. No. 4,227,836, owned by applicants assignee, discloses and claims one structure for permitting a silo unloader to be raised high enough into the silo roof to minimize interference with loading of silage.
U.S. Pat. No. 4,132,450 discloses a cable connection for a silo unloader of the type which is suspended by a single cable at the center of the silo roof, and which has a movable cable connection which permits the unloader to be hung in a substantially horizontal working position or in an inclined position when it is elevated for filling the silo.
U.S. Pat. No. 3,512,661 discloses a silo unloader of the single cable suspension type which has an adjustment for the connection between the suspension cable and the silo unloader so as to vary the pressure of the silo unloader sweep arm against the silo wall in use. The suspension is such that it necessarily causes the silo unloader to occupy an inclined position when it is elevated into the roof of the silo.